Congenital Pediatric GU Anomalies

Question 1

What are the common congenital abnormalities of the kidneys and collecting system?

Answer 1

• Multicystic Dysplastic Kidney (MCDK)
• Antenatal hydronephrosis
• Ureteropelvic Junction Obstruction (UPJO)
• Vesicoureteral Reflux (VUR)
• Ureteral Duplication
• Ureteroceles
• Ectopic Ureters

Question 2

What is the presentation, etiology, diagnosis, and management of Multicystic Dysplastic Kidney (MCDK).

Answer 2

• Most common cystic disease of childhood
• It has an estimated incidence of 1:2500 lives births, affecting males more than females and the left kidney more often than the right.
• Etiology is thought to be due to the abnormal development of the kidney caused by either:
  
  • Failed coordination of the ureteric bud and the metanephric blastema leads to the maldevelopment of the kidney
  • Early complete ureteral obstruction
• Diagnosis is most often made during prenatal ultrasonography
  
  • Characteristic findings on post-natal ultrasound are the presence of multiple, non-communicating cysts of differing sizes with minimal renal parenchyma
  • Confirmation can be made by demonstrating the lack of function of the affected kidney on nuclear renal scan
• Management of the MCDK has changed significantly in recent years
  
  • Although hypertension and development of renal tumors have been previously associated with the MCDK, it is now thought to be exceedingly rare
  • Most, if not all MCDK, will involute over time and thus, nephrectomy is seldom warranted
  • However, contralateral pathology such as vesicoureteral reflux and ureteropelvic junction obstruction of the contralateral kidney may be present in up to 30% of all patients
  • Thus, current management strategies have focused on conservative observation of the MCDK and identification and management of contralateral pathology

Question 3

What is the presentation, etiology, diagnosis, and management of antenatal hydronephrosis?

Answer 3

• The 20-week prenatal ultrasound is now the standard of care
• As a consequence, the diagnosis of antenatal hydronephrosis has increased
• The majority of antenatal hydronephrosis will resolve on its own (80%).
  
  • In the remainder, it is imperative to differentiate between hydronephrosis and obstruction, as not all hydronephrosis indicates obstruction.
• Postnatal diagnoses identified commonly secondary to antenatal hydronephrosis include:
  
  • Ureteropelvic junction obstruction (UPJO)
  • Vesicoureteral reflux (VUR)
  • Ureterovesical junction obstruction/ectopic ureter
  • Ureteroceles
  • Posterior urethral valves (PUV).

Question 4

What is the presentation, etiology, diagnosis, and management of Ureteropelvic Junction Obstruction (UPJO)?

Answer 4

• UPJ obstruction is the most common pathologic condition associated with persistent hydronephrosis
  
  • It represents an obstruction at the junction of where the ureter enters into the renal pelvis
  • It is more likely to affect males than females (5:2) and the left kidney more often than the right (5:2).
• The etiology of UPJ obstruction can be either intrinsic or extrinsic
  
  • The most common intrinsic cause is the presence of an adynamic ureteral segment
  • Extrinsic causes are more commonly found in older children and adults
  • The most common extrinsic cause is the presence of a crossing vessel, an accessory lower pole renal artery “crossing” anteriorly to the ureteropelvic junction.
• UPJ obstruction is often found on prenatal ultrasounds
  
  • Patients may also present with UTI, intermittent flank pain, hematuria, and renal calculi
• Diagnosis is often suspected based on ultrasound findings of severe hydronephrosis
  
  • A MAG3 diuretic renogram is often used to solidify the diagnosis.
• Management of UPJ obstruction centers on determining which kidneys are in danger of renal deterioration if left untreated
  
  • Surgical correction of UPJ obstruction is accomplished with a pyeloplasty.

Question 5

What is the presentation, etiology, diagnosis, and management of Vesicoureteral Reflux (VUR)?

Answer 5

• Most common cause of renal scarring in children!
• It is estimated to affect approximately 0.4% of the general population
  
  • VUR is more common in females than males (10:1) when presenting after a febrile UTI but is more common in males when found as part of the evaluation for antenatal hydronephrosis
  • There is a strong familial inheritance pattern with 60% of children and 40% of siblings also affected
  • There is also a higher rate of VUR among Caucasian
• VUR is thought to be due to an abnormality of the ureterovesical junction where there is an incompetency in the flap-valve mechanism
  
  • This is thought to be due to shortening of the intravesical ureter and deficiency of the trigonal musculature
  • The result is a laterally displaced ureteral orifice
• Diagnosis is typically made after a febrile UTI or as antenatal hydronephrosis
  
  • In children presenting with a UTI, it is estimated that up to 40% of children will have VUR
  • The gold standard for diagnosis is the Voiding Cystourethrogram (VCUG)
  • It is used to grade the severity of reflux on a scale of 1 to 5. Grading of VUR helps predicts the clinical course of the disease
• Spontaneous resolution is common especially in the lower grades of VUR (Grades 1-2) of upwards of 80% over 5 years
  
  • Therefore, the hallmark of treatment is the avoidance of UTIs
  • This may be accomplished with prophylactic antibiotics and/or an emphasis on good voiding patterns
  • Surgical correction with ureteral reimplantation is reserved to children at risk for recurrent UTIs and renal scarring
  • Higher grades of reflux (grades 4 and 5) are unlikely to resolve on its own and often require surgical correction (less than 10%)

Question 6

What is the presentation, etiology, diagnosis, and management of Ureteral Duplication.

Answer 6

• Ureteral duplication is often a radiographic finding without clinical significance
• The etiology of ureteral duplication is due to either the premature branching (incomplete duplication) or the presence of two distinct ureteral buds arising from the mesonephric ducts
• In complete duplications, pathology can be predicted based on the Weigert-Meyer rule
  
  • Following this rule, the ureter associated with the lower pole of the kidney inserts more laterally and refluxes, while the ureter of the upper pole of the kidney inserts more medially and will obstruct
  • This can result from an ureterovesical junction obstruction (UVJO), ureterocele, or an ectopic ureter

Question 7

What is the presentation, etiology, diagnosis, and management of Ureteroceles?

Answer 7

• Ureterocele are the saccular dilation of the distal ureter. Its reported incidence is approximately 1: 500-1: 4000
  
  • Girls are more commonly affected (4:1) and ureteral duplication is present in up to 95% of cases
  • In boys, it is more commonly associated with a single system
• Etiology is postulated to be the incomplete breakdown of Chwalla’s membrane, leading to early obstruction
  
  • Ureteroceles are classified as intravesical versus extravesical (extension past the bladder neck)
• Ureteroceles typically present as a finding on prenatal ultrasounds
  
  • It most commonly is associated with ureteral obstruction and hydronephrosis
  • Others may with UTIs, flank pain, bladder outlet obstruction, or as an interlabial mass.
• Diagnosis is confirmed by ultrasound findings of a thin-walled cystic structure within the bladder
  
  • A broad-based filling defect found on VCUG is also characteristic of an ureterocele
• Management of ureteroceles is controversial
  
  • Strategies are dependent on the degree of obstruction, viability of the associated renal parenchyma, risk of infection, and its impact voiding

Question 8

What is the presentation, etiology, diagnosis, and management of Ectopic Ureters?

Answer 8

• Ureters that do not insert in the normal position within the bladder
• These may be associated with both single as well as duplex collecting systems
• These ureters may be normal, reflux, obstruct, or both
• In girls, the insertion may be distal to the external urinary sphincter, resulting in incontinence
• In boys, the insertion is always proximal to the sphincter, and thus incontinence is not seen

Question 9

List the congenital anomalies of the urethra.

Answer 9

• Posterior Urethral Valve (PUV)
• Hypospadias

Question 10

What is the presentation, etiology, diagnosis, and management of Posterior Urethral Valve (PUV)?

Answer 10

• PUV is the most common cause of bladder outlet obstruction and an important cause of end-stage renal failure in boys
• The incidence is estimated to be 1 in 4000 live births.
• Etiology of PUV is the presence of a congenital obstructing membrane located in posterior urethra.
  
  • This membrane leads to a mechanical obstruction, resulting is dilation of the posterior urethra, bladder trabeculation, and possibly VUR, hydronephrosis, and renal dysplasia.
• PUV is most often diagnosed on prenatal ultrasound
  
  • Characteristic prenatal ultrasound findings include bilateral hydronephrosis and a thick-walled bladder with a dilated posterior urethra (the “key-hole” sign)
  • Oligohydramnios is a poor indicator of postnatal outcome
  • Postnatal diagnosis is made with VCUG.
• Acute management of PUV is medical stabilization of the neonate and catheterization to relieve the urinary obstruction
• Definitive treatment with an endoscopic valve ablation should be undertaken once the child has been stabilized
  
  • Long-term management of PUV centers on optimizing renal function and the attainment of urinary continence

Question 11

What is the presentation, etiology, diagnosis, and management of Hypospadias?

Answer 11

• Is the failure of the urethra to completely form to the tip of the penis
  
  • This results in a displaced urethra along the ventral aspect of the penis or perineum
• The incidence is reported to be 1 in 300 male births
• There is an increased incidence in industrial countries, leading to theories about environmental endocrine disruptors
  
  • However, no clear etiologic cause has been identified
• Diagnosis is made on physical examination
  
  • Characteristic findings on exam include a ventrally displaced urethral meatus, a dorsally hooded prepuce, ventral chordee, and a flatten glans
  • In cases of hypospadias associated with non-palpable testis, a diagnosis of Disorders of Sexual Development must be entertained
• The severity of hypospadias ranges from mild (located at the corona or glans) to severe (located at the perineum)
  
  • The location of the meatus and the severity of the associated chordee determine its functional impairment on urination and sexual function
• The foreskin is often used as part of the surgical repair
  
  • Thus, it is imperative not to circumcise a boy with hypospadias prior to evaluation by an urologist
  • Surgical correction of hypospadias typically occurs between 6-9 months of age

Question 12

List the congenital anomalies of the scrotum.

Answer 12

• Undescended testis (UDT)
• Hydrocele/Indirect hernia

Question 13

What is the presentation, etiology, diagnosis, and management of Undesceded testis (UDT)?

Answer 13

• Normal descent of the testis begins in the 3rd month of embryogenesis
  
  • Testes initially form near the kidney and migrate to the inguinal canal through the initial transabdominal phase
  • At the 7th month, the testis migrates down the inguinal canal to reach the scrotum by the 8th month, the inguinoscrotal phase
  • Normal descent of the testes is a complex interaction involving Mullerian Inhibiting Substance (MIS), the genitofemoral nerve, calcitonin gene-related peptide (CGRP), androgens, the gubernaculum, and gonadotrophin.
• Incidence of UDT is estimated to be 3-5% of newborns but only present in 1% of 1 year olds
• Spontaneous descent of the testis can occur within the first 6 months of life.
  
  • Prematurity increases the risk of UDT
• Diagnosis is made on physical exam. Classification of UDT includes:
  
  • Ectopic testes: abnormal location of the testis
  • Intracanalicular: within the inguinal canal
  • Intraabdominal: within the abdominal cavity
  • Retractile: able to be displaced into the scrotum. May be due to a hyperactive cremasteric reflex
  • Acquired undescended testis: a testis that at one point was located within the scrotum.
• Radiographic evaluation is unnecessary
  
  • In non-palpable testes, surgical exploration, most commonly with laparoscopy is indicated
• Treatment is with surgical correction
  
  • This is performed most commonly at 6 months of age or when diagnosed
• Long-term prognosis of UDT is good
• Potential long-term complications include:
  
  • Infertility: Paternity rates of 62% in bilateral cases, 90% in unilateral cases
  • Cancer potential: up to a 1% increased incidence of testicular cancer
    
    • The most common tumor is seminoma
    • There has also been a reported increased incidence in the contralateral, descended testis as well as an increased risk with delayed orchiopexy after 13 years of age

Question 14

What is the presentation, etiology, diagnosis, and management of Hydrocele/Indirect hernia?

Answer 14

• Incidence of 1-3% of full-term infants
  
  • The incidence is 3x greater in premature infants
  • It is more often seen on the right (2:1) with only 16% bilateral.
• Etiology is due to a patent processus vaginalis.
  
  • A large opening allowing intraabdominal contents to transverse into the scrotum indicates an indirect hernia, while a small opening only allowing fluid through is defined as a communicating hydrocele.
• Diagnosis is made by physical examination
  
  • Differentiation of a communicating versus a non-communicating hydrocele is based on fluctuation in size with increases in intraabdominal pressure
• Spontaneous closure of the processus vaginalis can occur up to 18 months of age
  
  • Surgical correction is recommended when the processus fails to close